Quick example of a simple paintjob, with virtually zero preparation and over 2 days to allow paint to dry.
1) Start with a hopper:
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/20140402_182739_zpsf8c51a46.jpg
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/20140402_182725_zps98f1fb05.jpg
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/20140402_182705_zps57a56fbb.jpg
2) Do the minimal preparation - take it apart and put all pieces safely away
No primers have been used, and the only semblance of a base coat are the first coats
3) Paint the inside silver in a cople of coats
(Theres a reason for that which is for me to deal with at a later date, nothing to do with the paint job)
Only the top area for the paintballs needs to be silver, the front lower area is the battery bay, the rear lower area to the feedneck will hold the workings of the Halo.
These will remain untouched as its intended that the hopper will work.
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/B2577041-769C-420C-9E64-8AE632DDE51A.jpg
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/334FAED8-7573-4CB2-B44A-267024279BEB.jpg
4) Paint the outside one colour in a lot of light multiple coats.
Not pictured at this stage, it was just painted tan, but you can see the plain tan in teh slot for the battery cover.
Let this dry a little between coats, but leave properly overnight to dry after all the coats.
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/13CBB546-C722-42B8-ABE3-8A5D5748EF98.jpg
5) Slightly assemble if some form of pattern match is required.
(Keep the pieces seperate and the pattern wont match accross joins)
For the Halo there is no need to assemble properly, screw together etc. Just put the 2 shell halves together and then the battery cover. The cover will hold the hopper together.
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/3D97A160-9531-4B84-A98B-069230028FB1.jpg
6) Wave the hopper around in front of a spray can, make light sweeps - in this case a green.
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/621274B5-59CF-481E-9C83-9A86B9329980.jpg
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/32D23E77-571C-4C25-BADA-1AB2311ED2C3.jpg
Keep going until you are happy - for any form of effective pattern it ought to have more colours to reflect shade etc.
If the colours get too heavy then add a light spray of the base colour again.
7) Let it dry a little, and then disassemble again.
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/01B1F590-7469-4D97-9983-D80D75B2DF90.jpg
8) Check and cleanup any paint that should not be there
The edges will need a clean off to let the sides slot together neatly. There is not realy much work to do here, rub it clean with some thinner etc. But if there is anything sensitive then it should have been masked in the preparation. Now will be too late - my favourite masking is some tape, and newspaper over large areas (I have even used clingfilm in the past)
http://i608.photobucket.com/albums/tt168/tommikka/HALO B/ED5EAB4C-6993-42E8-9BFC-073D23D91902.jpg